Depends on the audience and the application. As Photoshop and AutoCad are both mentioned, I think that's the benchmark and not something like Facebook that wouldn't benefit as much from running as a desktop client.
On a side-note, didn't Facebook just release a new UWP app and didn't they regret going the HTML5 route to start with (not focusing on native apps)?
They were fine for years without any kind of desktop app, and the HTML5 backtracking was just for mobile. I don't think they ever said they regretted being web-only on desktop from the start. In fact I think it is even a big reason for their success - would Facebook have taken off if it had an installer?
Maybe not for those cases, but a lot of apps aren't as demanding as those. So I don't think you can say in general that the web can't compete with desktop apps, maybe only just for specialist cases. The web is good enough that it didn't stop Facebook becoming a billion-dollar company. Mobile is a different matter, but think on desktop how many services are fine to work web only on desktop with no desktop app (especially if they have a mobile app).
I don't think this is the case. Facebook never needed desktop apps, did they? The web worked great for them.